I need to use a different UI for Windows Installer for which I am using MsiSetExternalUI API and using the messages received in my handler to make changes on custom UI (Progress bar etc.). Everything is going fine except Custom Action.
I have a custom action that gets executed even before WelcomeDlg. It has an entry in InstallUISequence table. Now the problem is, Its not appearing in my external UI handler. If I move that Custom Action entry to InstallExecuteSequence table, it works like a charm...!!
I am referring this links,